Spray head



Oct. 17, 1950 i J, PEEPS 7 2,526,405

SPRAY HEAD Filed Nov. 26, 1945 i INVENTOR. l2 Flg DONALD J. PEEPS ATTORNEY Patented Oct. 17, 1950 SPRAY HEAD Donald J. Peeps, Toledo, Ohio, assignor to The De Vilbiss Company, Toledo, Ohio, a corporation of Ohio Application November 26, 1945, Serial No. 680,873

3 Claims.

This invention relates to a spray or discharge head for heating and applying coating material highly viscous, or even solid, at ordinary temperatures and to such a head which is particularly suitable for the application of materials of this type which require exceptionally high temperatures to render them sufliciently fluid for effective use. 7

Considerable difficulty is encountered in maintaining the high temperatures usually required. Atomizing air absorbs a definite amount of the heat of the material while the latter is passing through the spray gun. Even though this air is warmed in this way, it is later cooled by ex- 'pansion when it leaves the spray nozzle and as it impinges against the material. This direct contact with the chilled'air has afurther cooling eiiect upon the material, which'must not only be Well heated to be effectively atomized but also must retain sufficient heat to flow out smoothly upon reaching the surface to be coated.

Substantial heat may also be lost by radiation from the outer surface of the spray head, as heat is readily conducted by the metal of which the body is constructed from the material passage to the outside surface of the body.

A primary object of the invention is the provision'of means for effectively heating the material within the passage of the spray or discharge head.

A further objectof the invention is the retention of the high temperature of the material as it is discharged and shaped into flattened form.

An additional object is the provision of a spray head which will-lose a minimum amount of heat through radiation.

Another object is the provision of means for discharging the material unatomized in flattened cross section and simultaneously striking the material with atomizing air.

A still further object is the provision of means for electrically insulating the forward end from the rear end of the spray head except for the material needle valve which has contact with each end, and means for passing electricity into the material inlet connection of the spray head and through the needle to the forward end of the spray head.

The features of the invention which contribute to the attainment of these objects are the use of the needle as an electrical heating unit located centrally and axially within the material passage;' a spray head structure in which there is aminimum of heat conducting metal between the walls of the material passage and the outside sur- 2 face of the spray head from which the heatmay be radiated; a nozzle structure having means to discharge the material in fan spray form with a minimum use of air for the purpose; and a material nozzle shape that induces the air to flow over the surface of the nozzle into impingement with the material. I

In the accompanying draWing- Fig. 1 is a side elevation partly in section of 'a spray head embodying my invention; 7

Fig. 2 is a vertical section taken on the line 22 of Fig. 1;' V

Fig. 3 is a vertical section, taken onthe line 33 of Fig. 1, across the longitudinal axis of the discharge tip, needle valve and the triangular spider;

Fig. 4 is a fragmentary longitudinal vertical section of the discharge end of a spray head embodying a slight variation from the form of my invention as shown in Fig. l; and

Fig. 5 is a fragmentary exterior'view of the rearward portion of the forward body section; and Fig. 6 is a section of the body taken on the line 6-6 of Fig. 5.

The spray head embodying my invention as shown in Fig. 1 has a forward body section I and a rearward body portion 2. The two parts are held'tightly together by interlocking nuts 3 and E which are respectively threadedly connected to sections l and 2. The nuts 3 and 4 do not directly bear upon each other because of the interposed electrical non-conducting ferrule 5. Another annular separating member 6 of like insulating composition is centrally located between the two body parts, coaxial with and forming a portion of the material passage 1 through the spray head.

A conventional material discharge tip 8 is fastened to the forward end of body section 1.

.Over this is mounted a special supplemental tip 9 with a slotted discharge opening It. The outer surface of the tip surrounding the opening II] is semi-spherical in shape. In the preferred embodiment illustrated in Fig. 1 there is no air admitted to the interior of tip 9 to be mixed with the material prior to its discharge through slotted opening l0. However, should atomizing requirements or other factors make such an arrangement desirable, some air may be introduced into tip 9 through several grooves spaced around the. inner tapered seating surface of the tip 9 surrounding the standard tip 8. The spray head of Fig. 4 has grooves of this type one of which is shownat II. p

Preferably then the material assumes a flattened shape as it passes through the orifice l0 3 and takes this step toward its final form without undergoing the chilling contact of compressed air ordinarily used for this shaping purpose.

Mounted over the supplemental material tip 9 is air cap i2. This has a central opening I3 through which the rounded end of tip 9 protrudes.

A substantial degree of atomization is secured from the air issuing through the annular space between the edge of opening I3 and the adjacent cylindrical section of tip 9. This air follows the curved surface of the rounded end of tip 8, forwardly and inwardly, and impinges against the coating material as it issues from the slotted opening [0.

The cap is also provided with paired ports I2 and I5 for delivering supplemental atomizing and flattening air jets against the central stream of atomized material.

The atomizing air enters the spray head through passage I6 and reaches the inner side of air cap [2 by way of annular chamber I'I, six circumferentially spaced passages I8 cut through the threads beneath nut 3, and annular chambers I9 and 20.

A material needle cut-off valve 2| has a conical end which seats in the outlet opening of tip 8, and in the conventional manner extends, at the other end, through and beyond the rear end of the spray head where it is connected for reciprocation to the trigger mechanism of the gun to which the spray head may be attached.

In this case the needle valve 21 is made of a metal particularly serviceable as an electrical heating element.

This spray head is designed for attachment to a hose carrying an electrical conductor for delivering current to the hose connection at the spray head end. With the hose connected to the material inlet 24 of the spray head, the current flows into the rear spray head body section 2 from which it enters the needle valve 2|. Aspreviously described, section 2 is electrically insulated from the forward body portion I by spacers 5 and 6.

The cru'rent travels through needle 2| until it reaches triangular spider 22 with which the needle has sliding contact. The current then passes through spider 22 into tip 8 into which the spider is press fitted. From the tip 8 the electrical current enters body section I and completes its circuit through ground terminal 23 and a suitable return wire fastened to it. Body sections I and 2, spider 22 and tip 8 are of course made of brass or other metal suitable for electrical conductors.

It may be noted by reference to the drawing that the walls of the material passage are practically surrounded by air passages. This air, while carrying away some heat, is a much poorer heat conductor than metal and therefore acts to heat insulate the material passage from the outside of the spray head body. Thus, loss of heat by conduction laterally is minimized.

I wish it understood that my invention is not limited to any specific construction or arrangement of parts, as it is capable of numerous modifications and changes without departing from the spirit of the invention.

Having thus described my invention what I claim. as new and desire to secure by Letters Patent is:

1. In a spray head for applying a heated coat- 4 ing material, a semi-spherical material discharge nozzle with a slot-like discharge port on its forward end, said nozzle being positioned on the forward end of the spray head, a centrally ported air cap placed over the nozzle and defining with it a forwardly facing annular atomizing air port located around the nozzle at a point of the latters greatest transverse diameter, an elongated material passage terminating with the slot-like discharge port, a material needle valve serving as both a valve and as an electrical heating element, said needle valve extending axially through the passage and seating at the forward end of said passage, two spaced electrical supply connections on the spray head, and two spaced metallic portions on the spray head, each contacting an oppositeend of the needle valve and associated with one of said connections whereby an electrical current is directed through the needle valve.

2. In a spray head for applying a heated material, a discharge nozzle in the forward end of the'spray head, an elongated material passage terminating at'the' nozzle, a material needle valve serving as both a valve and as an electrical heating unit, said needle valve extending axially through the passage and seating at the forward end of said passage, forward and rearward sections of the spray head, means joining said sections, electrical non-conducting material associated with said means and insulatingly separating the sections whereby the needle valve is the sole electrical conductor between the sections, a metallicportion of the forward section of the spray head having sliding contact with the needle valve, a'metallic portion of the rearward section of the spray head also having sliding contact with the needle valve, and an electrical connection on each section associated with the metallic portion, whereby an electrical circuit from one section to the other by way of the needle valve. is formed and the needle valve, thus energized, heats the material passing through the elongated material passage.

3. In a spray head for applying a heated material, a longitudinal material passage, an elongated material valve constituting an electrical heating element and extending axially Vlihill said passage, metallic parts of the spray head contacting opposite ends of said'needle valve, non-conductor bushing means separating said parts, and connections for directing a flow of electricity through the needle valve by way of said metallic parts.

DONALD J. PEEPS.

REFERENCES CITED The following references are of record in the file of this patent:

I UNITED STATES PATENTS Numb er 2,434,911 Denyssen 1 Jan. 27, 

